Energy Structure and Electro-Optical Properties of Organic Layers with Carbazole Derivative
Thin Solid Films 2014
K. Pudzis, A. Vembris, Inese Muzikante, R. Grizbovskis, Baiba Turovska, J. Simokaitiene, S. Grigalevicius, J.V. Grazulevicius

Phosphorescent organic light emitting diodes are perspective in lighting technologies due to high efficient electroluminescence. Not only phosphorescent dyes but also host materials are important aspect to be considered in the devices where they are a problem for blue light emitting phosphorescent molecules. Carbazole derivative 3,6-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole (TCz1) is a good candidate and has shown excellent results in thermally evaporated films. This paper presents the studies of electrical properties and energy structure in thin films of spin-coated TCz1 and thermally evaporated tris[2-(2,4-difluorophenyl)pyridine]iridium(III) (Ir(Fppy)3). The 0.46 eV difference of electron conduction level between TCz1 and Ir(Fppy)3 compounds was obtained from the cyclic voltammetry and photoconductivity measurements. Temperature modulated space charge limited current (TM-SCLC) method is used to measure the local trapping states for charge carrier in the energy gap. The TM-SCLC measurements for the system TCz1 + 8 wt.% Ir(Fppy)3 show a trapping state with the value of 0.4 eV which is comparable to the conduction level difference of these materials. It allows to conclude that Ir(Fppy)3 molecules act as electron traps in the TCz1 matrix and the TM-SCLC method is applicable to investigate dopants as trapping states. To show the trap effect, an organic light emitting diode was made where the electroluminescent layer was a spin-coated host-guest system of TCz1 with incorporated 8 wt.% Ir(Fppy)3.


Atslēgas vārdi
Bipolar conductive organic materials; Temperature modulated space charge limited current; Local trapping states; Electroluminescence
DOI
10.1016/j.tsf.2013.12.031
Hipersaite
http://www.sciencedirect.com/science/article/pii/S0040609013020956

Pudzis, K., Vembris, A., Muzikante, I., Grizbovskis, R., Turovska, B., Simokaitiene, J., Grigalevicius, S., Grazulevicius, J. Energy Structure and Electro-Optical Properties of Organic Layers with Carbazole Derivative. Thin Solid Films, 2014, Vol.1074, 549.-558.lpp. ISSN 0040-6090. Pieejams: doi:10.1016/j.tsf.2013.12.031

Publikācijas valoda
English (en)
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